There are a number of chronic diseases with poorly understood etiologies that contribute substantially to the morbidity of human populations and result in significant expenditures of public health dollars. Environmental agents may produce some of this disease, and identification of associations between exposures and certain diseases would presumably lead to the prevention of morbidity. Other than cancer, few chronic diseases have received much attention in studies of environmental hazards, yet other diseases might be the more common, although less obvious or dramatic, results of exposure to such hazards. The Epidemiology Branch is working towards a program in environmental epidemiology that will address the role of environmental factors in the etiology of some less well studied chronic diseases or sources of exposure. The program currently includes a number of studies of chronic disease or cancer epidemiology. Foremost among these is a case-control study of risk factors for chronic renal failure and related work involving development of a renal disease classification scheme for use in etiologic studies. The feasibility of other studies that relate to risk factors for chronic renal failure is being explored. Other studies in the environmental epidemiology program include a recently completed study of the relationship of parental smoking and subsequent cancer development in adult offspring and investigation into the etiology of Reye's Syndrome.